Reverse transcriptase activity in bovine bone marrow: purification of a 66-kDa enzyme

The presence of reverse transcriptase (RT) activity in a DNA-binding protein complex of the goat bone marrow has been reported earlier from our laboratory. Here we report a procedure for the purification of the enzyme with RT activity from bovine bone marrow and show that the basic function is associated with a approximately 66-kDa protein. This enzyme can use RT specific homopolymers as template and short oligonucleotides as primers, while displaying a Mg(2+)-ion requirement. Eukaryotic RTs have been shown to have endogenous RNAs associated with the enzymes. Evidence is presented here to show that some endogenous RNAs are associated with the RT activity in bovine bone marrow. Even though the enzyme activity appears to be associated with a approximately 66-kDa protein, the results indicate that for a full expression of its activity, the enzyme needs to interact with a 55-kDa protein that co-purifies with the enzyme during ion-exchange chromatography.